Lecture 5: Control systems and homeostasis.

Question 1

What is the range of temperature variation?

Answer 1

36 to 37.5 degrees celsius.

Question 2

True or false? Temperature variation is the same across all ages.

Answer 2

False. Temperature variation is larger in the elderly and young.

Question 3

At what other times are there variations in temperature?

Answer 3

During menstruation, there is a 1 degree increase. Also approximate 0.6 degree difference diurnally.

Question 4

List the 4 main ways we lose heat.

Answer 4

Convection, conduction, radiation, evaporation.

Question 5

What do the sympathetic outflow in the brain regulate in terms of temperature?

Answer 5

Skin arterioles (vasodilation and constriction). Also regulates sweat glands. Motor nerves however control shivering.

Question 6

Describe the mechanism of fever.

Answer 6

Fever is caused by pyrogens either via:

• Exogenous means (endotoxins from bacteria, such as the lipopolysccharide on their outer membrane)
• Endogenous means (such as the release of cytokines).

Ultimately results in the synthesis of PGE2, which can be inhibited by aspirin, which helps to reset core temperature as regulated by the hypothalamus.